This past year the Sleep and Neurodevelopmental Service scheduled over 180 overnight sleep studies ordered by twelve different institutes, many of them more than half for pediatric patients. We have collected sleep data on several distinct cohorts including children with childhood onset schizophrenia, obsessive compulsive disorder, autism, McCune Albright Syndrome, Chronic Fatigue Syndrome, Sickle Cell Disease, Neurofibromatosis, as well as for people with various disorders of neurodevelopment with both known and unknown genetic causes. We are working with our collaborators to try to identify unique sleep signals that help define the disorders under study and therefore outline paths for potential therapeutic intervention. Some of our earliest work, looking at sleep in children with autism, helped us understand that there is a lot of information in the way the brain sleeps and that sleep neurophysiology also contains important information about the way the brain matures. We recently published our findings showing that in a large cohort of children with autism, sleep markers, called spindles, were reduced compared to children with typical development and also reduced when compared to children with developmental delays who did not also have autism. This work suggests that some markers only found in sleep, might be related to behavioral differences in children. We have recently completed a study of sleep neurophysiology in young children at risk for autism due to severe language delays through a natural history study of children ages 12 - 18 months (Protocol 11-M-0144, NCT01339767), where we were able to explore longitudinally how very early differences in sleep rhythms and maintenance may relate to aberrant development and the onset of autistic symptoms. That analysis and publication is forthcoming. These findings highlight the importance of looking at the sleeping brain during development for some of the earliest clues regarding neurodevelopmental disorders. Yet, considerable gaps in knowledge still exist in our understanding of sleep measurements and how these change during the early periods of brain development. Filling in these gaps may aid in the earliest identification of mental health disorders. We work closely with the Neurodevelopmental and Behavioral Phenotyping Service to best associate changes in the sleeping brain to neurodevelopmental stages in typical and atypical neurodevelopment. A major focus of the research arm of the Service is to develop a comprehensive battery of sleep measurements as a mainstay of clinical assessment of children at risk for neurodevelopmental disorders. Through our efforts with researchers from many different disciplines, we hope to create and initiate standardized protocols for collecting sleep data on children. To that end, the Service hosted a workshop to develop and promote Electrophysiologic Sleep Phenotyping (ESP) as a mainstay of the clinical assessment of children at risk for neurodevelopmental disorders. The online summary of that Workshop can be found at the following link: https://www.nimh.nih.gov/news/events/2017/sleep-and-neurodevelopment-workshop-electrophysiologic-sleep-phenotyping-esp.shtml. In 2018, the focus was on the role of animal models and their contribution to our understanding of how sleep contributes to healthy development of the brain. Future protocols informed by these meetings would include comprehensive behavioral assessments at the time of the sleep exam in order to best identify normal and abnormal developmental trajectories at the earliest possible opportunity.